Protecting various articles of different sizes and shapes packaged within generally square or rectangular packing cartons during handling and shipment is a common problem in the packaging industry. This problem is most commonly addressed by placing a shock absorbing cushioning material around the article or articles to cushion the articles from the shocks incident to handling and shipment.
In some circumstances, this cushioning material is a loose, friable material completely surrounding the articles, and in others, the articles are wrapped in sheets of cushioning material. Another cushioning material currently in use is foam-in-place polyurethane which is injected into the cartons and a mold forms a cavity the size and in the shape of the article being packaged. This cavity must be left open at the top to permit the placement therein of the article. Several ways of closing the top of this cavity and protecting the top of the article have been used. One such way has been to form a cavity closing member on one or more of the carton closure flaps of foam-in-place polyurethane. Another has been to form a separate closure member of cushioning material which is placed in the cavity above the item before closing the top of the package. A particular type of such separately formed closure member is formed by filling a pre-formed bag, generally formed of plastic, with a cushioning material (usually foam-in-place polyurethane) and then closing the top of the bag to form a pillow-like cushion which is then placed above the article packaged inside a container. Although such cushions can provide the desired protection, the fabrication thereof has heretofore been a strictly manual operation because no suitable automated means exist for either filling or for making and then filling plastic bags with cushioning materials to form cushion-type pillows. Such manual operations are cumbersome, time-consuming, expensive and result in non-uniform and sometimes inadequate cushioning members.
Machines for making plastic bags have, of course, been available for some time. Such machines have included those which transfer bag materials to different stations for forming the bags, filling the bags, sealing the bags and then delivering the bags; machines for opening and loading of pre-formed bags; machines for forming bags from folded over plastic; machines for drawing bagging material upwardly so that relatively heavy, solid objects can be dropped therein to form the bag; machines for filling and separating previously formed bags from a stock supply; and some machines that form and fill plastic bags from plastic tubing from a stock supply.
All of these machines suffer certain disadvantages which prevent their effective use to form packaging cushions. In particular, because one preferred cushioning material is plastic foam, generally formed from foam precursors which react in situ, any machine suitable for forming such cushions must be suitable for handling foam precursors and filling formed bags with such precursors. Thus, machines which form bags by loading with heavy solid objects, or by allowing solid materials to be dropped therein, or which by their structure can only load solid objects into the bags, are generally not suitable for the handling of foam precursors.
Additionally, because various packaging applications require that many different sized objects be packed in many different sized containers, bagging machines which can only form, fill and close bags of a single size are generally not useful for forming packaging cushions. Consequently, existing machines for handling serially attached bags from a stock supply of bag material, for forming and filling one particular size of bag from stock plastic material, or for shaping particular bags around particular objects, are unsuitable for the many packaging applications for which foam-filled cushions are necessary.
Finally, because foam precursors generate gases during the foam formation process, any process for producing packaging cushions made from plastic bags and foam precursors must deal with the gases produced. Specifically, machines or processes which form totally sealed bags are unsuitable because they provide no method for the off-gases to escape unless the bags formed and filled with foam are kept open for a significant period of time prior to sealing, an alternative which would greatly slow production process.
It is thus an object of the present invention to provide a method and apparatus for forming foam cushions for packaging purposes which comprise plastic bags substantially sealed at both ends and enclosing a plastic foam.
It is a further object of this invention to provide a packaging cushion from which gases generated as the foam precursors form foam can escape while the foam is retained therein.
It is another object of this invention to provide a method and apparatus for forming, opening, filling and sealing plastic bags formed from a stock supply of plastic tubing characterized by the elimination of handling of cut bags during formation and filling and which eliminates the problem of the off-gases generated during foam formation.
It is a further object of this invention to provide an apparatus for forming foam cushions of a variety of sizes which makes most efficient use of foam and which can be quickly and easily adjusted to form different sizes as may be so desired.